JP4657699B2 - Earthquake damage assessment system and damage assessment unit - Google Patents

Description

  The present invention relates to a damage assessment system for a bridge during an earthquake and a damage assessment unit. Specifically, the invention is mainly used for judgment of damage to a bridge such as a reinforced concrete bridge pier as a road bridge. The present invention relates to a system that can quickly and accurately perform sex diagnosis and damage degree diagnosis.

  The diagnosis of damage to bridges after earthquakes, such as earthquakes, diagnosis of continued availability, and damage level diagnosis are currently based on visual inspection from the outside, and generally require judgment by experts. . Therefore, since the number of experts is limited and it takes time to dispatch experts to the site, it takes a lot of time to diagnose damage to bridges in the earthquake area, and it is necessary to make judgments especially at night. It is difficult for specialists to determine when there is damage or when visual inspection such as damage to the underground or underwater is not possible.

  Development research on health monitoring technology for the purpose of detecting aging of structures has been conducted, but this technology cannot be diverted to disaster diagnosis. In other words, it is difficult to measure the large strain and large deformation area generated in the bridge due to the earthquake disaster with the current monitoring technology. In addition, since it is impossible to predict when the earthquake will occur, monitoring through an external power source is difficult to realize in terms of maintenance costs and system configuration. Sufficient monitoring is possible depending on the power outage caused by the earthquake. There is a possibility that it cannot be done.

  In addition to the above, vibration detectors are installed on the piers that make up the bridge structure, and these vibration detectors detect the vibration of the piers during an earthquake and transmit the vibration waveforms to the relay station by wire to the relay station. There is also known a bridge characteristic inspection device that temporarily accumulates and then wirelessly transmits to a measurement unit, and the determination unit of the measurement unit determines the safety of the bridge from the vibration waveform (see, for example, Patent Document 1). ). However, with this device, the determination is performed by the determination unit provided at the relay station, and the vibration waveform data is transferred via a wired line. Some data may not be delivered, and it may be impossible to determine a pier that lacks this data.

Japanese Unexamined Patent Publication No. 07-128182

  Therefore, the present invention solves the problems of the conventional one, can easily and quickly determine the degree of damage to the bridge during an earthquake, and can objectively and efficiently predict whether or not the bridge can be used after an earthquake. An object is to provide a bridge damage degree determination system and a damage degree diagnosis unit.

但し、Ｔは、変化後の橋梁の固有周期、Ｔ0は、変化前の橋梁の固有周期、μは、応答塑性率である。 In order to solve the above-mentioned problem, the invention according to claim 1 is an acceleration installed in a bridge pier head of the bridge structure in an earthquake bridge damage degree determination system that determines a degree of damage to a bridge structure after an earthquake. The acceleration response record of the pier head at the time of the earthquake is obtained by the sensor , and the change of the natural period before and after the earthquake is obtained from this acceleration response record. The response plasticity rate corresponding to is obtained, and it is determined that the bridge is damaged when the response plasticity rate exceeds a predetermined value set as a threshold value in advance .

Where T is the natural period of the bridge after the change, T0 is the natural period of the bridge before the change, and μ is the response plasticity factor.

The invention according to claim 2 is a damage diagnosis unit used in the earthquake damage determination system for a bridge according to claim 1, wherein damage to a bridge structure is detected based on the acceleration sensor and detection data of the acceleration sensor. Built-in microcomputer for determining, a communication device for transmitting the determination result when the microcomputer determines that the structure has been damaged, a memory for storing the sensor data and the calculation result, and supplying power to them The power source was housed in one predetermined container and packaged.

  Since the present invention is configured as described above, the degree of damage to the bridge at the time of the earthquake can be determined easily and quickly, and the availability of the bridge after the earthquake can be predicted objectively and efficiently. That is, from the acceleration response record showing the behavior of the bridge structure at the time of the earthquake, the availability of the bridge after the earthquake can be automatically and simply confirmed quickly, and various coping activities in the event of a large earthquake In addition to helping to ensure a quick initial dynamics, it is possible to objectively and efficiently determine the damage of structures, which will contribute to an efficient and rational recovery plan after an earthquake.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1A is a perspective view showing an outline of a bridge damage level determination system and a damage level diagnosis unit during an earthquake. Reference numeral 51 denotes a road bridge as a bridge structure, which is a target for determining the degree of damage in the present system. The road bridge 51 includes a plurality of reinforced concrete piers 52 and an upper part installed on these piers 52. It consists of a bridge 53 that is a structure.

  A bridge damage level determination system (hereinafter referred to as a determination system) 1 during an earthquake includes a damage level diagnosis unit (hereinafter referred to as a diagnosis unit) 2 having an acceleration sensor installed on each bridge pier 52, and these diagnoses. The management computer 3 mainly receives the diagnostic information from the unit 2 and processes the information, and after the occurrence of the earthquake, the diagnostic unit 2 voluntarily manages damage to the installed pier 52. The management computer 3 side can quickly and surely understand the damage situation caused by the earthquake of the entire road network including the road bridge 51 and can provide various kinds of countermeasure information.

  The management computer 3 is installed at a predetermined location away from the road bridge 51 and is connected to a communication device (not shown). The management computer 3 is a large general-purpose computer (in consideration of the necessary capacity defined by the number of diagnostic units 2 and other processes other than the processing of information obtained from the diagnostic units 2, costs). Any one of a main frame computer), a workstation, a personal computer (personal computer), and the like is appropriately selected and used. That is, the management computer 3 receives the damage determination results of the plurality of bridge piers 52 and performs processing related to the soundness (usability) of the entire road network including the road bridge 51. This processing result is output as traffic information. For example, when it is determined that the road bridge 51 is unusable, the surrounding section is closed and a detour is presented to prevent secondary disasters and to ensure smooth traffic during disasters.

  A diagnostic unit 2 that acquires vibration data for detecting damage to the pier 52 due to an earthquake is attached to the head of each pier 52. That is, the base of the pier 52 is fixed to the ground, and the head of the pier 52, more preferably the top of the pier 52 is selected as a place where vibrations caused by seismic waves transmitted through the ground can be clearly observed. A diagnostic unit 2 is installed at the end. Further, these diagnostic units 2 are each configured as an autonomous unit capable of performing a predetermined series of operations independently without receiving power supply from the outside or receiving a command from the outside.

  That is, as shown in FIG. 1B, the diagnostic unit 2 includes an acceleration sensor main body 4 for detecting the acceleration of the pier 52 vibrated by an earthquake and acquiring vibration waveform data, and the acceleration sensor main body. A processing computer 5 which is a microcomputer for performing a determination operation and a record storage operation for processing data measured by 4 in a predetermined manner, and a communication device 6 for wirelessly transmitting a necessary notification to the external management computer 3 based on the processing result. And a memory 7 for storing and storing predetermined sensor data and calculation results for a long time, and a power supply unit 8 for supplying power necessary for the operation of each of these units 4 to 7 without depending on an external power source. They are packaged and all contained in a single small container that can be sealed. Then, in the diagnostic unit 2, the acceleration sensor body 4 detects the response acceleration of the pier 52 at the time of the earthquake, and the processing computer 5 obtains a change in the natural period of the pier 52 from the detected response acceleration and based on the change, the earthquake When the damage to the pier 52 is determined and the processing computer 5 determines that the pier 52 has been damaged, the determination result is transmitted to the management computer 3 using the communication device 6 and notified. Furthermore, the power supply unit 8 that supplies operating power to each of the units 4 to 7 can be self-supplied.

  This diagnostic unit 2 houses an electrical configuration in a casing (not shown) having weather resistance such as waterproof and dustproof and durability, and even if installed in the field, it is subject to fluctuations in various external environments. The internal structure can be protected in a predetermined manner. The weight and dimensions of the diagnostic unit 2 are set so that they can be handled easily and can be easily carried by human power.

  The diagnostic unit 2 essentially uses a micro electro mechanical system (MEMS) sensor as the acceleration sensor main body 4, and the MEMS sensor is used as a microcomputer board (hereinafter referred to as a microcomputer) that constitutes the processing computer 5. It is mounted directly on the board). That is, the MEMS sensor as the acceleration sensor is an electric component that is arranged and incorporated on the microcomputer board.

  This is the object of the acceleration sensor body 4 because the physical quantity to be detected is the acceleration of the object, and the object is the pier 52 having a much larger mass than the diagnostic unit 2. If it is attached to the pier 52, it can be detected without affecting the acceleration of the pier 52 in the event of an earthquake, and the acceleration sensor body 4 does not need to be exposed outside the diagnostic unit 2. This is because even if it is housed inside the diagnostic unit 2, its detection operation can be safely performed. The acceleration sensor body 4 is a MEMS sensor that is inexpensively supplied by mass production and can be integrated with a microcomputer board. As a result, the acceleration sensor can achieve power saving and cost reduction.

  The processing computer 5 is configured by arranging predetermined components such as a CPU, a memory for program execution, and an acceleration sensor body 4 on a microcomputer board as a circuit board. A storage memory 7 is provided. The memory 7 for recording and storage has a sufficient storage capacity for storing a predetermined amount of actual measurement data acquired by the acceleration sensor body 4 when an earthquake occurs, and supplies a minimum operating current required for storage from the power supply unit 8. The stored actual measurement data can be stored for a long time after the occurrence of the earthquake so that it can be collected at any point in time. ing.

  The communicator 6 has a predetermined communication function and is connected to a microcomputer board and an antenna (not shown). Instead of installing a wired line between the diagnostic unit 2 and the management computer 3, a wireless line formed by a wireless line is used. LAN (Local Area Network) is formed. Therefore, the diagnostic unit 2 is connected to the wireless LAN as a terminal in accordance with a predetermined communication protocol, and enables communication such as data exchange with the management computer 3. As described above, since the communication processing between the diagnostic unit 2 and the management computer 3 uses the data distribution function provided in advance in the LAN function, the number of the diagnostic units 2 can be arbitrarily increased or decreased. For this reason, the whole structure of the determination system 1 as a fixed facility can be flexibly changed according to the road bridge 51 as a target for determining the degree of damage, and the application range can be expanded.

  The diagnostic unit 2 is a self-contained sensor system that does not depend on power supply from an external power source. That is, each diagnostic unit 2 has a built-in power supply unit 8 configured as a semi-permanent power source. The entire unit of the diagnostic unit 2 (acceleration sensor main body 4, microcomputer board as processing computer 5, communication device 6) The memory 7) covers the power consumed.

  The built-in power supply unit 8 as a semi-permanent power source is a power generation unit (not shown) that generates power using sunlight, wind power, hydraulic power, vibration, or the like as an energy source, and stores this power and supplies it in a practical and stable manner. And an electric storage unit (not shown) using an electric capacitor such as an electric double layer capacitor. Depending on the natural environment in which the bridge structure 51 is installed, natural energy may be any of sunlight, wind power, hydraulic power, or a combination of these as appropriate, as an energy source for power generation. As the configuration, a general configuration is appropriately selected and used.

  Therefore, since the semi-permanent power source configured as described above is built in, the diagnostic unit 2 can eliminate the need for external power supply and frequent battery replacement.

  According to the diagnostic unit 2 configured as described above, the handling can be facilitated and the installation cost can be reduced. That is, the diagnostic unit 2 can be easily handled because its weight and external dimensions are set so as to be transportable by human power. In addition, the diagnostic unit 2 has a self-contained power supply unit 8 and has a wireless communication line secured between the diagnostic unit 2 and the management computer. Is installed at the detection location and a predetermined operation test is completed, it can be immediately put into operation, and the installation cost can be reduced.

  Next, a damage determination method based on a change in natural period will be described.

  First, the allowable response plasticity ratio of bridge piers is one of the main indicators in the seismic design of bridges in newly constructed bridges. Also, it is known that the existing plastic bridge has a strong correlation between the response plasticity factor and the damage degree. For this reason, the response plasticity rate can be used as an index of the degree of damage.

  Note that the response plasticity μ is the maximum amplitude of the response displacement waveform generated in the structure when a seismic motion waveform is applied to the target structure, and a static load is applied to the target structure. In this case, if the displacement amount when yielding statically is δy, it can be defined as a value obtained by δ / δy.

  Next, the relationship between the response plasticity factor and the natural period will be described. Generally, in a reinforced concrete member, a complete elastoplastic relationship is established in the relationship between load and displacement. Based on the premise that there is a perfect elasto-plastic relationship, it can be derived that the rate of change of the natural period before and after the reinforced concrete single column pier damage is equal to the square root of the response plasticity rate. Below, the process of deriving will be described.

That is, the natural period T of the pier structure is expressed by the following equation (1) from the mass m of the pier structure and its spring constant K as an equation of simple vibration.

  The assumption of complete elasto-plasticity is shown in the graph of FIG. If the pier structure is not damaged before the earthquake occurs, that is, if the external force P applied to the pier structure is lower than Py, the response displacement δ due to this external force becomes an elastic deformation that is completely proportional to the external force P, and the spring constant K Is Py (external force at the elastic limit = yield yield strength) / δy (displacement at the elastic limit = yield displacement), that is, K0. Therefore, the natural period T does not change.

  On the other hand, as shown in the graph of FIG. 2 (b), when the external force P caused by this earthquake exceeds the yield strength Py when the earthquake occurs, the response displacement δ exceeds the yield displacement δy while maintaining the yield strength Py. As it grows, the reinforced concrete becomes a plastically deformed state that softens while being damaged. The spring constant K after softening can be expressed by Py / δ (maximum response displacement) and is smaller than K0. For this reason, the natural period T becomes longer than before the damage.

Here, from the relationship of equation (1), the natural period T0 before the pier is damaged is expressed by the following equation (2) using the spring constant K0 before being damaged.

If the natural period after being damaged is T and the rate of change of the natural period before and after the damage is defined as T / T0, the above formulas (1) and (2) are substituted into this and rearranged. (3) Equation is obtained.

From the graph of FIG. 2B, the spring constant K0 and the spring constant K are expressed by the following equations (4) and (5), respectively.

Therefore, substituting and organizing these equations (4) and (5) into the above equation (3) yields the following equation (6).

  Accordingly, since the response plasticity ratio μ is defined as δ / δy, it can be understood from the equation (6) derived in this way that the natural period change rate is equal to the square root of the response plasticity ratio.

  In addition, whether the correlation between the natural period change rate and the response plasticity was established with sufficient accuracy was verified by a shaking table experiment using a pier scale model of about 1/4 of the actual size. That is, from this experimental result, as shown in the graph of FIG. 2C, the response plasticity rate (vertical axis) obtained from the measured natural period and the response plasticity rate (horizontal axis) obtained from the measured response displacement It can be understood that each of the values can be plotted almost on a straight line. From this, it is clearly recognized that there is not only a correlation between the two values, but also a direct proportional relationship with sufficient accuracy. .

  From the above explanation, an acceleration response record is obtained at the time of the earthquake, and the change in the natural period of the bridge structure before and after the earthquake is obtained from the acceleration response record. From this change, the response plasticity index that is an index of the damage degree of the bridge structure is obtained. It is possible to calculate and determine whether the bridge is damaged. That is, the diagnostic unit 2 detects that the natural period of the bridge structure “continuously detected during the earthquake” has received some damage from the “natural period T0 at the time of no damage (before change)” and the “natural characteristic after change”. The system automatically identifies the transition to “period T” and calculates the response plasticity rate μ from the “change rate” that indicates how quickly it has changed. The presence or absence of damage to the bridge structure is judged. In this case, a predetermined value based on the allowable plasticity factor is set in advance as a threshold, and it is automatically determined that the bridge is damaged when the calculated response plasticity exceeds the predetermined value. In addition, the natural period can be calculated using acceleration response recording, for example, from the Fourier spectrum of the waveform at an appropriate time (about 10 seconds) during the period when the vibration seems to be stable. An appropriate analysis method is employed, and any analysis method that can reliably determine the presence or absence of damage in consideration of safety may be simple with respect to analysis accuracy and the like, and is not particularly limited. Further, the unit of the natural periods T0 and T used for the calculation is appropriately selected from seconds (sec), milliseconds (msec), etc. according to the characteristics of the bridge structure.

  Next, the damage degree determination algorithm used in the diagnostic unit 2 will be described.

  Using the determination method based on the above correlation, as shown in FIG. 3, a damage degree determination algorithm for making a primary determination (determination of damage presence / absence) and a secondary determination (diagnosis of the degree of damage) is formulated. The created algorithm is programmed, the created program is incorporated in the diagnostic unit 2, and the diagnostic unit 2 is mounted on the microcomputer board so as to be able to operate in accordance with the algorithm. That is, a ROM (Read Only Memory) storing a program for executing the above algorithm is mounted on a microcomputer board with a built-in acceleration sensor that constitutes the processing computer 5 which is the main subject of the diagnosis unit 2. Yes.

  The overall operation of the determination system 1 configured as described above will be described. That is, with the occurrence of an earthquake, the diagnostic unit 2 installed on the head of the pier 52 sequentially executes each process of the input stage, the calculation stage, and the output stage.

  At the input stage, it is determined whether or not to start taking in data. It is determined from the acceleration data detected by the acceleration sensor body 4 whether a data collection start event (earthquake event) has occurred. If it is determined that an earthquake event has occurred, the data is stored in the memory and the following processing is started. .

  Next, in the calculation stage, the calculation of the natural period and the determination of the damage degree are sequentially performed. The natural period is calculated by Fourier transform or wavelet transform. At that time, data pre-processing and post-processing such as window setting and filter processing are also performed. The determination of the damage degree is based on the response plasticity rate calculated from the rate of change of the natural period before and after the earthquake. By comparing this response plasticity rate with the preset allowable plasticity rate, the primary determination is made. It is determined whether or not there is damage and whether or not the pier 52 after the earthquake is usable.

  Finally, the determination result is output at the output stage. As the primary determination result, the result of whether or not the pier 52 after the occurrence of the earthquake determined in the calculation stage is usable is output and notified to the outside by the wireless communication device 6. Built-in data storage for storing information necessary for detailed secondary judgments that are performed externally, that is, response acceleration waveforms from the start of an earthquake event to the end of primary judgment, maximum values, and primary judgment results The data is stored in the memory 7 so that it can be recovered later through the wireless communication device 6. The collected data will contribute to detailed damage analysis and recovery planning.

  As described above, according to this determination system, the acceleration response record at the time of the earthquake is acquired by the acceleration sensor installed at the head of the pier, and damage to the pier due to this earthquake is determined. It is easy, a large number of piers can be targeted for damage determination, and a wide application range can be obtained. That is, in general, the base of a bridge pier is usually damaged, but this base is often located in the soil or water, so it is difficult to install the sensor, and direct measurement at the damaged site is difficult. Accompany. On the other hand, in this determination system, the response acceleration of the structure is used as information for damage detection, and this response acceleration is detected by a sensor installed on the head other than the base. Therefore, the difficulty associated with sensor installation can be minimized.

  In addition, the diagnostic unit that makes up this judgment system calculates changes in the natural period of the bridge structure before and after the earthquake using a microcomputer board directly connected to the acceleration sensor, and immediately determines whether there is damage to the bridge structure from the calculation results. In addition, since the determination result is output, the accuracy and speed of detection and determination can be sufficiently secured.

  That is, since the detection data from the acceleration sensor is directly calculated and processed on the spot without being transferred to another place, the time required for damage detection and judgment can be minimized. In addition, it is possible to eliminate the delay time caused by the transfer, and it is possible to avoid the deterioration or missing of the data quality at the time of the transfer and to improve the accuracy and reliability of detection / judgment.

  Further, since only the determination result determined on the diagnostic unit side is transferred to the management computer side and notified, the communication load can be reduced and information can be transmitted quickly and smoothly. Therefore, the management computer is quickly notified of the damage status of each pier where the diagnostic unit, which is a part of the bridge structure, is installed, and the management computer knows the overall damage status of the bridge structure. can do. Therefore, the management computer can easily and quickly provide the degree of damage to the bridge at the time of the earthquake, objectively and efficiently predict whether or not the bridge will continue to be used after the earthquake, and implement various measures to prevent secondary disasters. Information can be generated automatically.

  Further, the diagnostic unit transmits only the determination result, and the response acceleration record of the detection target structure acquired at the time of the earthquake is stored in a memory and collected by a wireless LAN or the like. Can be saved for later studies without destroying detailed records. That is, immediately after the earthquake, the communication network is expected to be disrupted, so only the determination result is transmitted. For this reason, the burden on the communication network can be minimized. On the other hand, detailed records such as raw unprocessed raw data are stored in a memory so that they can be collected at a later date.

  In the above embodiment, the diagnostic unit is configured to notify that the pier where the diagnostic unit is installed has been damaged due to the earthquake, so that the pier is damaged. You may comprise so that it may notify that this pier is undamaged when it determines with having not. Therefore, in this configuration, the management computer that is notified guarantees that the pier is undamaged by the judgment of the diagnostic unit, so that the possibility of continued use of the pier after the earthquake occurs is sufficiently reliable. Can be diagnosed with a certain degree of security. In this case, a time zone that is divided into a notification for damage notification and a notification for no damage is set in advance. However, it may be possible to improve the assurance in the case of diagnosis of continuous use in the continuous use diagnosis.

  Moreover, although each diagnostic unit and management computer were connected so that both could exchange data directly and wirelessly, it is not limited to this, and a wireless repeater may be interposed between them.

1 shows an earthquake damage determination system for a bridge according to the present invention, (a) is a schematic perspective view showing the overall configuration of the determination system, and (b) shows an outline of a damage diagnosis unit and a management computer of the determination system. It is a functional block diagram. The determination method of the same determination system is shown, (a) is a graph showing the relationship between load and displacement when the input (external force) is small and no damage occurs, and (b) receives a large input (external force). The graph which showed the relationship of the load-displacement in case damage arises, (c) is a graph which shows the verification result by a shaking table experiment. It is the outline | summary of the damage degree determination algorithm which the damage degree diagnostic unit of the determination system same as the above uses.

Explanation of symbols

1 Bridge damage assessment system during an earthquake 2 Damage assessment unit 3 Management computer 4 Acceleration sensor body (acceleration sensor)
5 Processing computer 6 Communication device 7 Memory for record storage 8 Power supply 51 Road bridge 52 Bridge pier 53 Bridge (superstructure)

Claims (2)

In the earthquake damage determination system for bridges that determines the degree of damage to bridge structures after an earthquake,
The acceleration response record of the pier head at the time of the earthquake is obtained by the acceleration sensor installed on the pier head of the bridge structure, and the change of the natural period before and after the earthquake is obtained from this acceleration response record. The response plasticity rate corresponding to the degree of damage of the bridge structure is obtained based on the formula of the Bridge damage assessment system during earthquakes.

Where T is the natural period of the bridge after the change, T0 is the natural period of the bridge before the change, and μ is the response plasticity factor. A damage diagnosis unit used in the earthquake damage determination system for a bridge according to claim 1,
The acceleration sensor, a microcomputer that determines damage to the bridge structure based on detection data of the acceleration sensor, and a communication device that transmits the determination result when the microcomputer determines that the structure is damaged, A disaster diagnosis unit characterized in that a memory for storing sensor data and calculation results, and a built-in power source for supplying power to these memories are housed and packaged in one predetermined container.

Images